1. Field of the Invention
The present invention generally relates to an apparatus and system for applying limited torque to a plug. In one aspect, the invention relates to an apparatus that can be secured to a new or used plug to limit the torque that can be applied in a closing direction to the plug when the plug is used to seal a container.
2. Description of the Related Art
A typical sealing assembly for a container comprises a plug, a tab used to rotate the plug, a gasket associated with the plug, and a flange secured within a container. When a torque-providing device (e.g., wrench, torque wrench, etc.) applies torque (i.e., a rotational force) to the tab in a closing direction, the plug rotates in the closing direction such that the plug is threadably received within the flange. As rotation in the closing direction continues, the gasket is compressed between the plug and the flange. Compression of the gasket between the plug and the flange is expected to form a liquid-impermeable seal, thereby sealing the container and preventing the container from leaking.
Unfortunately, if an inappropriate amount of torque is administered to the plug, the liquid-impermeable seal will not be formed and the container can leak. For example, if too much torque is applied to the plug, the gasket can be too forcefully compressed, potentially damaging the gasket. On the other hand, if too little torque is applied to the plug, the gasket will not be compressed forcefully enough and the liquid-impermeable seal cannot be achieved. In either case, leaking of the container can result. To ensure the proper application of torque, and consequently prevent the containers from leaking, several solutions have been suggested.
One solution known to combat over-torquing the plug and/or over-compressing the gasket calls for the use of a torque wrench to provide torque to the tabs. A torque wrench is a device that is calibrated to permit the application of a limited amount of torque to a component such as, for example, the plug. When the limited amount of torque has been delivered, the torque-wrench provides a signal to a torque wrench operator by xe2x80x9cslippingxe2x80x9d, xe2x80x9cgivingxe2x80x9d, and/or xe2x80x9cbreaking-awayxe2x80x9d. The torque wrench can be configured such that the limited torque that is applied to the plug equals the torque necessary to form the liquid-impermeable seal with the compressed gasket. Therefore, by using the torque wrench, the limited torque is theoretically guaranteed to be delivered. However, the torque wrench is often improperly or unskillfully used. All too frequently, the torque wrench operator fails to perceive, or simply ignores, the signal provided by the torque wrench. As such, the torque wrench operator can apply, despite the torque wrench If signal, too much torque to the plug. Therefore, the gasket is over-compressed and the sealing assembly can permit the container to leak. Thus, the solution of employing the torque wrench to deliver the limited amount of torque is often ineffectual.
Another solution to the problem of over-torquing the plug and/or over-compressing the gasket proposes using a torque-limiting device with the plug. As known in the art, such torque-limiting devices typically contain an independent, helical compression spring. For example, in U.S. Pat. No. 4,809,869 to Cosgrove, et. al., pawls, biased by a helical compression spring, engage with ratchet teeth as torque is applied. When the torque becomes excessive, the pawls and ratchet teeth disengage. Also, in U.S. Pat. No. 3,715,075 to Blau, et. al., coupling members, biased by a helical compression spring, engage with groove-like recesses as torque is applied. Again, when the torque becomes excessive, the coupling members and the groove-like recesses disengage. While the torque-limiting apparatus of both Cosgrove and Blau may be useful for some applications, each apparatus critically relies on the independent, helical compression springs to limit the amount of torque. Since each helical compression spring is an integral component within the torque-limiting device/plug combination, it would be difficult, if not impossible, to efficiently fit, retro-fit, and/or adapt the torque-limiting devices disclosed in Cosgrove and Blau to a used, existing, recycled, or previously manufactured plug. Thus, such torque-limiting devices fail to provide the most practical and cost-efficient solution to the problem of over-tightening the plug and/or over-compressing the gasket which can result in container leakage.
Another proposed solution to the problem of over-torquing the plug and/or over-compressing the gasket involves a more indirect remedy. This solution uses a sealing cap (i.e., a safety cap) in combination with the typical sealing assembly. After the plug has been rotated to compress the gasket between the plug and the flange, the sealing cap is crimped onto, and over, the flange and/or the sealing assembly. Thus, the sealing cap can protectively cover the plug and the gasket. This indirectly prevents the container from leaking even if the gasket fails. While the use of the sealing cap may prevent the container from leaking, the sealing cap neglects the underlying problem (i.e., a damaged or ineffectual gasket). Further, if the plug is to be subsequently removed from the container, reused, and/or recycled, the sealing cap must be damaged to access the plug. A new sealing cap can be required each time the container is to be sealed and/or resealed. As such, maintaining container integrity can become expensive. Therefore, sealing caps provide a less durable and/or less comprehensive solution to the fundamental problem of over-torquing the plug and/or over-compressing the gasket.
Thus, an apparatus and system that can limit torque applied to a plug by a torque-producing device, permit a gasket to be compressed between the plug and a flange in a container until a liquid-impermeable seal is formed, prevent damage to the gasket, and seal the container, would be highly desirable. Likewise, the apparatus would be constructed of few components and be utilized with used and/or existing plugs.
In one aspect, the invention provides an apparatus for limiting torque applied by a torque-providing device. The apparatus can comprise a torque ring rotatably seatable upon a plug and a torque collar securable to the plug and holding the torque ring rotatably captive. The torque ring includes a torque ring aperture that engages the torque-providing device and an axially-protruding resilient finger that provides a resisting force. The torque collar has a torque collar aperture that receives the torque-providing device and a finger aperture that receives and engages the axially-protruding resilient finger. When torque is applied to the torque ring by the torque-providing device in a closing direction, the axially-protruding resilient finger engages the finger aperture to transfer torque from the torque ring to the torque collar. This permits the torque collar to rotate the plug in the closing direction until torque overcomes the resisting force of the axially-protruding resilient finger. When this occurs, the axially-protruding resilient finger disengages from the finger aperture. As a result, the torque ring continues to rotate in the closing direction independent of the torque collar and the plug.
Disengagement of the axially-protruding resilient finger from the finger aperture can occur when the axially-protruding resilient finger is biased toward the plug, biased away from the torque collar, flattened by the torque collar, forced axially downwardly, radially urged downwardly, and/or bent flush with the torque ring. Therefore, disengagement can cause the axially-protruding resilient finger to temporarily deform such that the finger is not axially-protruding from the torque ring. Also, disengagement can ensure that a gasket, used in conjunction with the plug, is not damaged and a container is sealed. Further, the plug can be removed from being sealably inserted within the container without damage occurring to the plug.
The resisting force can be determined by friction generated between the axially-protruding resilient finger and the torque collar or by upward protrusion of the axially-protruding resilient finger and friction generated between the axially-protruding resilient finger and the torque collar. Because the resisting force is mechanically determined, the apparatus can eliminate human error by automatically disengaging when the torque applied to the torque ring overcomes the resisting force.
In one embodiment, the apparatus can be employed with used plugs. In other words, the apparatus can be retro-fitted upon the used plugs. In another embodiment, torque can be applied to the torque ring by the torque-providing device in an opening direction. When this occurs, the axially-protruding resilient finger engages the finger aperture such that torque is transferred to the torque collar and causes the plug to rotate in the opening direction until the torque is no longer applied by the torque-providing device.
The axially-protruding resilient finger can include a front surface and a friction surface, the friction surface providing a resisting force. Also, the torque collar can define a sliding surface while the finger aperture can define a camming surface.
In another aspect, the invention comprises an assembly for limiting torque applied by a torque-providing device. The assembly can include a plug having a periphery, a gasket disposed upon the plug proximate the periphery, and an apparatus secured to the plug. The apparatus can comprise a torque ring and a torque collar. The torque ring, rotatably seatable upon the plug, can include a torque ring aperture that engages the torque-providing device and an axially-protruding resilient finger that provides a resisting force. The torque collar, securable to the plug and holding the torque ring rotatably captive, can include a torque collar aperture that receives the torque-providing device and a finger aperture that receives and engages the axially-protruding resilient finger.
When torque is applied to the torque ring by the torque-providing device in an opening direction, the axially-protruding resilient finger engages the finger aperture to transfer the torque from the torque ring to the torque collar. This permits the torque collar to rotate the plug in the opening direction until the torque is no longer applied by the torque-providing device.
Also, when torque is applied to the torque ring by the torque-providing device in a closing direction, the axially-protruding resilient finger engages the finger aperture to transfer the torque from the torque ring to the torque collar. This permits the torque collar to rotate the plug in the closing direction and compress the gasket until the torque overcomes the resisting force of the axially-protruding resilient finger. When torque overcomes the resisting force, the axially-protruding resilient finger disengages from the finger aperture. This results in the torque ring continuing to rotate in the closing direction independent of the torque collar and the plug such that the torque applied to the plug in the closing direction is limited and the compressed gasket is not damaged. Thus, containers using the assembly can be sealed and prevented from leaking.
In another aspect, the invention comprises a system for sealing. The system can include a plug having a periphery, a gasket disposed upon the plug proximate the periphery, a container, and a torque-limiting apparatus. The container can include a flange that threadably receives the plug and the gasket. Thus, the flange and the plug can compress the gasket thereby sealing the container.
The container in the system can be a 55-gallon metal drum and the flanges can be two-inch flanges and/or three-quarters inch flanges. The system can further comprise a cap seal that provides protection from leaks. The cap seal is typically secured to the plug after the plug has been secured in the flange within the container.
In another aspect, the invention comprises a method of limiting torque applied by a torque-providing device. The method comprises providing a plug having a torque-limiting apparatus which includes a torque ring and a torque collar. The torque ring, rotatably seatable upon the plug, can have a torque ring aperture that engages the torque-providing device and an axially-protruding resilient finger that provides a resisting force. The torque collar, securable to the plug and holding the torque ring rotatably captive, can have a torque collar aperture that receives the torque-providing device and a finger aperture that receives and engages the axially-protruding resilient finger.
Next, torque is applied, in a closing direction, to the torque ring using the torque-providing device. This results in the axially-protruding resilient finger and the finger aperture engaging to translate torque to the plug. The plug is thereby rotated, in the closing direction, until torque overcomes a resisting force of the axially-protruding resilient finger. When the resisting force is overcome, the axially-protruding resilient finger and the finger aperture disengage such that the torque ring rotates relative to the torque collar. Thus, the amount of torque that can be applied to the plug is limited.
The method can further comprise inserting the plug into a flange disposed within a lid of a container. The method can also include compressing a gasket on the plug against the flange when the plug is rotated in the closing direction to seal the container. Further, the method can insure that damage to gaskets is inhibited and/or prohibited by disengaging the torque ring and the torque collar when the resisting force is overcome.
Additionally, the method can comprises applying torque, in an opening direction, to the torque ring using the torque-providing device. Opening-direction torque can cause the axially-protruding resilient finger and the finger aperture to engage and translate torque to the plug. As such, the plug can rotate in the opening direction until the torque-providing device ceases to apply the torque.